Had an hour to kill today & just happened to be very near to a VW dealership, so spent the time taking a quick look at the Up.
For those whose priorities are for economy over performance, I'd say this car is going to give the 500 & New Panda a run for their money. Interestingly the salesman said that VW had targeted the Up against those two cars specifically & he was getting a lot of interest from existing FIAT owners who were close to trade-in time.
When I bought my 500, the only serious competition for a petrol ecocar came from the C1/Aygo/107 & the Alto/Pixo, both of which feel cheap & nasty in comparison (sorry deeyup). The Up is a much more serious contender & I'm sure other manufacturers will also be making a concerted effort to target what may soon be the only real growth sector in the new car market.
The 500 has held an essentially unchallenged position since launch, but that is changing, and I feel sure it won't be long before FIAT will have to seriously discount the car to stay in the league tables, and as I've posted before, once that happens, secondhand values will likely plummet.